Emergency weapon for firing high-velocity grenade rounds

ABSTRACT

A shoulder-supported weapon for firing high-velocity grenade rounds includes means for reducing the high-velocity and recoil forces to acceptable limits comprising an oversize barrel chamber which permits expansion of the case upon discharge of the round and immediate escape of the discharge gas between the case and projectile during initial acceleration of the projectile into flight. The escaping gas is vented from the chamber into a canister around the barrel and then back through a second set of ports into the barrel bore forwardly of the projectile. The gas escape system is closed when the projectile passes the second set of ports and the remaining trapped gas is used to propel the projectile from the barrel.

United States Patent [72] Inventor Stanley D. Silsby Granby, Mass. [21] Appl. No. 873,426 [22] Filed Nov. 3, 1969 [45] Patented Oct. 12, 1971 [73] Assignee The United States of America as represented by the Secretary of the Army Continuation-impart of application Ser. No. 776,953, Nov. 19, 1968, now abandoned.

[54] EMERGENCY WEAPON FOR FIRING HIGH- VELOCITY GRENADE ROUNDS 5 Claims, 6 Drawing Figs.

[52] US. Cl 89/14 R, 42]] F [51] Int.Cl ..F4lc 21/12, F41f 17/00 [50] Field of Search 42/1 F, 76; 89/1, 1.3, 14, 14.3,43, 1.703; 102/38,65.2,43

[5 6] References Cited UNlTED STATES PATENTS 1,864,374 6/1932 Romberg et a1. 42/76 2,801,416 8/1957 Evansetal 89/1 3,059,367 10/1962 Rosebush 42/76 Primary Examiner-Benjamin A. Borchelt Assistant Examiner-Stephen C. Bentley Attorneys-Harry M. Saragovitz, Edward J. Kelly, Herbert Berl and Albert E. Arnold, Jr.

ABSTRACT: A shoulder-supported weapon for firing highvelocity grenade rounds includes means for reducing the highvelocity and recoil forces to acceptable limits comprising an oversize barrel chamber which permits expansion of the case upon discharge of the round and immediate escape of the discharge gas between the case and projectile during initial acceleration of the projectile into flight. The escaping gas is vented from the chamber into a canister around the barrel and then back through a second set of ports into the barrel bore forwardly of the projectile. The gas escape system is closed when the projectile passes the second set of ports and the remaining trapped gas is used to propel the projectile from the barrel.

PATENTEUUBTIZIBTI 67 SHEET 1 [IF 2 Fi l INVENTOR ATTORNEYS EMERGENCY WEAPON FOR FIRING HIGH-VELOCITY GRENADE ROUNDS The above-identified patent application is a continuationin-part of applicants previously filed patent application Ser. No. 776,953, filed Nov. 19, 1968, now abandoned.

The invention described herein may be manufactured, used and licensed by or for the government for governmental purposes without the payment to me any royalty thereon.

BACKGROUND OF THE INVENTION Most helicopters with offensive capabilities are armed with launchers for automatically firing 40 mm. grenade rounds such as the M384 HE round. These rounds have high-velocity characteristics with long-range capabilities and consequently produce recoil forces so high that it has been impossible to fire them heretofore from shoulder-supported weapons. Consequently, although helicopters when shot down may have on board a large supply of these grenade rounds they cannot be used by the crash survivors for defensive or offensive purposes when away from the launchers in the downed aircraft.

SUMMARY OF THE INVENTION It is, therefore, the principal object of this invention to pro vide for crash survivors of those aircraft which are armed with 40 mm. grenade launchers an emergency-type shoulder weapon having means for reducing the velocity and recoil forces generated by the 40 mm. high-velocity rounds when fired so that the weapon may be fired from the shoulder without discomfort or injury to the shooter.

Further objects and advantages of the invention will be apparent from the following specification and the accompanying drawings which are for the purpose of illustration only:

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a fragmentary, partially cross-sectioned view of the emergency weapon showing the grenade round chambered in the barrel ready to be fired;

FIG. 2 is an enlarged cross-sectional view taken along line 22 of FIG. 1;

FIG. 3 is a cross-sectional view taken along line 33 of FIG. 2 but showing the case of the grenade round expanded by discharge thereof and the discharge gas passing between the projectile and case;

FIG. 4 is a view similar to FIG. 3 of an alternate embodiment wherein the weapon is adapted for adjustable control of its range; and

FIG. 5 is a cross-sectional view taken along line 5-5 of FIG. 4.

DESCRIPTION OF A PREFERRED EMBODIMENT Shown in the drawings is a shoulder-type weapon 12 for firing a high-velocity grenade round 14, such as the 40 mm. m384 HE round, that consists of a case 16 and a grenade projectile 18 held by press fit to the front end of the case. Projectile 18 is provided with a pair of longitudinally spaced rifling bands 19 having the same outside diameter as the case 16, and extending rearwardly from the rear one of the rifling bands is cylindrical portion 20 which leads rearwardly to an inwardly tapering portion 21. Case 16 is cylindrical in configuration with a rim 22 of larger diameter formed at the rear end thereof. The front portion of case 16, extending about 0.5 inches from the front end thereof, is thinned down around the inside thereof at 23 and such thinned portion has restrictive contact with cylindrical portion 21 for about 0.3 inches to hold projectile 18 to the case.

Weapon 12 includes a barrel 24 which is pivotally mounted to receiver 26 so that it can be swung open from a closed firing position for loading round 14 therein. When round 14 is loaded in barrel 24, case 16 is received by a chamber 28 formed in the rear end of barrel 24 and projectile 18 is received by bore 30 thereof, which is rifled at 31 to form lands 32 and grooves 34. Chamber 28 is counterbored from the rear end to form a recess 36 for matingly receiving rim 22. When round 14 is fully chambered in barrel 24 it is held centered to bore 30 and chamber 28 by the reception of rim 22 in recess 36 and the contact of projectile 18 with lands 32. Also, a space of approximately 0.3 inches separates the rear side of the one of the rifling bands 19 which has abutting contact with case I6 from the rear of rifling 31.

Chamber 28 has a diameter x which is formed larger, as predetermined, than diameter y of case 16 so that an enclosed compartment 38 of toroidal configuration is formed between the walls of the case and chamber when round 14 is loaded in barrel 24. Compartment 38 permits the expansion of case 16 upon discharge of round 14 and the difference between diameters x and y kis sufficient to achieve the desired result described hereinafter while remaining within the limits of expansion, up to the point of rupture, of the material from which the case is fabricated. With the M384 HE round, a difference of approximately 0.160 inches is found to be effective in achieving the desired result. A plurality of apertures 42 extend radially through barrel 24 from bore 30 in a transverse plane immediately forward of the front end of case 16 when chambered so that the rearmost edges of the apertures are at least flush with the front end thereof. A plurality of orifices 44 extend through the barrel from grooves 34 forwardly of the nose of projectile 18 and in the same plane, as shown in FIGS. 1, 3 and 4.

A canister 46 encircles the rear portion of barrel 24 so as to enclose apertures 42 and orifices 44 and to form with the outside of the barrel a closed pressure-chamber 48 which has communication with bore 30 through the apertures and orifices.

Thus, when round 14 is chambered and fired by the weapons firing mechanism (not shown) thinned portion 23 at the front end of case I6 is immediately expanded by the force of the discharge gas against the wall of chamber 28. This immediately permits the escape of the discharge gas, as shown in FIG. 3, between case 16 and projectile 18, through an opening 50 formed by the expansion of the case during the initial acceleration of the projectile While the inertia thereof and the resistance of rifling bands 19 to the engraving actions of lands 32 are being overcome. Some of the gas passing through opening 50 bypasses projectile 18 along grooves 34. More passes through apertures 42 into pressure chamber 48 and therefrom back into bore 30 through orifices 44 until projectile 18 is moved forwardly thereof so that sufficient discharge gas is bled to the atmosphere, without producing recoil reaction, to have weapon l2 operable from the shoulder. When projectile 18 moves along bore 30 to where it is forwardly of orifices 44 the remaining energized gas in bore 30 and pressure chamber 48 is trapped therein and is used to propel the projectile from barrel 24. It is readily seen that the amount of gas pressure acting against projectile 18, which determines its velocity and the recoil forces, is determined by the sizes of apertures 42 and orifices 44, the distances therebetween and the size of pressure chamber 48.

Tests have shown that through the velocity and recoilreducing capabilities of weapon 12 the range of rounds 14 can be reduced from 2,200 meters to a few feet and with the recoil reaction be appropriately reduced to where it is almost imperceptible.

Shown in FIGS. 4 and 5 is an alternate embodiment of the invention wherein weapon 12 is adapted so that the amount of gas applicable against projectile 18 can be adjusted to vary the range thereof within the limits wherein the shooter can withstand the resulting recoil impact.

In this embodiment, pressure chamber 48 is completely formed within the canister, now bearing reference number 51, by means of a sleeve 52 which is integrally welded to the inside thereof to fully enclose the pressure chamber. Sleeve 52 is provided with a first set of holes 54 which are registrable with apertures 42 and a second set of holes 56, which are simultaneously registrable with orifices 44. Sleeve 52 is rotatable on a bearing portion 58 of barrel 24 so that holes 54 and 56 are displaceable relative to apertures 42 and orifices 44, whereby the degree of communication between bore 30 and pressure chamber 48 is adjustable to regulate the amount of discharge gas which will be bypassed around projectile 18 when round 14 is fired. Canister 51 is releasably held in a selected position, relative to barrel 24, by detent means 60.

I wish it to be understood that I do not desire to be limited to the exact details of construction shown and described, for obvious modifications will occur to a person skilled in the art.

I claim:

1. The combination comprising an ammunition round including a case, a front end of said case, and a projectile releasably retained by said case for forward extension therefrom, a firearm barrel, a chamber in said barrel to receive said round for discharge, a bore extending from said chamber for receiving said projectile, said chamber having a diameter greater than that of said case to permit sufficient expansion thereof respective to said projectile responsive to round discharge for escape of the gases generated by the discharge between said projectile and said case during initial displacement of said projectile therefrom, and means for trapping a portion of the discharge gas and applying the trapped gas against said projectile for forward displacement thereof along said bore, said means comprising a canister, a sleeve fixed gas tight to the inside of said canister, a pressure chamber between said canister and said sleeve therein, a bearing portion form around said barrel forwardly of said chamber for journaled cooperation with said sleeve to rotatingly mount said canister on said barrel, a plurality of apertures extending from said bearing portion to said bore in a transverse plane coincident with the plane including said front end, a plurality of orifices extending from said bearing portion to said bore forwardly of said apertures, a first set of holes extending through said sleeve to said pressure chamber and being disposed for simultaneous registry with said orifices, a second set of holes extending through said sleeve to said pressure chamber and being disposed for simultaneous registry with said apertures when said first set of holes are in registry with said orifices, and means adjustably rotating said canister respective to said barrel for displacing said first and second holes relative to said orifices and apertures respectively to vary the degree of communication therethrough between said pressure chamber and said bore.

2. The combination as defined in claim 1 wherein said round is of the type of 40 mm. M384 HE round and the difference between the diameters of said case and said chamber is of the order ofO. inches.

3. The invention as defined in claim 1 and including a compartment of toroidal configuration formed between at least the front portion of said case and the correspondingly portion of said chamber by the difference between the diameters thereof to permit expansion of said case relative to said projectile responsive to the gases generated by the discharge of said round, and an opening formed between said front end and said projectile by the expansion of said case.

4. The invention as defined in claim 3 and including means for delaying displacement of said projectile from said case during escape of the discharge gases through said opening.

5. The combination as defined in claim 4 wherein said barrel bore is provided with rifling comprising a plurality of lands each including a rear end, said case comprises an annular portion at the front end thereof thinned down around the inside thereof, said projectile comprises at least one rifling band disposed in contact with said front end when said round is received by said chamber and arranged to be engraved by said lands during displacement of said projectile along said bore and a cylindrical portion located rearwardly of said rifling and in restrictive contact with said thinned down portion for retaining said projectile in said case, and wherein said delaying means comprises said rear ends spaced relative to said rifling band so that the resistance thereof to the engraving action of said lands cooperates with the inertia of said projectile in delaying the displacement of said projectile from said case during the escape of the discharge gas between said thinned down portion when expanded by the discharge gas and said projectile. 

1. The combination comprising an ammunition round including a case, a front end of said case, and a projectile releasably retained by said case for forward extension therefrom, a firearm barrel, a chamber in said barrel to receive said round for discharge, a bore extending from said chamber for receiving said projectile, said chamber having a diameter greater than that of said case to permit sufficient expansion thereof respective to said projectile responsive to round discharge for escape of the gases generated by the discharge between said projectile and said case during initial displacement of said projectile therefrom, and means for trapping a portion of the discharge gas and applying the trapped gas against said projectile for forward displacement thereof along said bore, said means comprising a canister, a sleeve fixed gas tight to the inside of said canister, a pressure chamber between said canister and said sleeve therein, a bearing portion form around said barrel forwardly of said chamber for journaled cooperation with said sleeve to rotatingly mount said canister on said barrel, a plurality of apertures extending from said bearing portion to said bore in a transverse plane coincident with the plane including said front end, a plurality of orifices extending from said bearing portion to said bore forwardly of said apertures, a first set of holes extending through said sleeve to said pressure chamber and being disposed for simultaneous registry with said orifices, a second set of holes extending through said sleeve to said pressure chamber and being disposed for simultaneous registry with said apertures when said first set of holes are in registry with said orifices, and means adjustably rotating said canister respective to said barrel for displacing said first and second holes relative to said orifices and apertures respectively to vary the degree of communication Therethrough between said pressure chamber and said bore.
 2. The combination as defined in claim 1 wherein said round is of the type of 40 mm. M384 HE round and the difference between the diameters of said case and said chamber is of the order of 0.160 inches.
 3. The invention as defined in claim 1 and including a compartment of toroidal configuration formed between at least the front portion of said case and the correspondingly portion of said chamber by the difference between the diameters thereof to permit expansion of said case relative to said projectile responsive to the gases generated by the discharge of said round, and an opening formed between said front end and said projectile by the expansion of said case.
 4. The invention as defined in claim 3 and including means for delaying displacement of said projectile from said case during escape of the discharge gases through said opening.
 5. The combination as defined in claim 4 wherein said barrel bore is provided with rifling comprising a plurality of lands each including a rear end, said case comprises an annular portion at the front end thereof thinned down around the inside thereof, said projectile comprises at least one rifling band disposed in contact with said front end when said round is received by said chamber and arranged to be engraved by said lands during displacement of said projectile along said bore and a cylindrical portion located rearwardly of said rifling and in restrictive contact with said thinned down portion for retaining said projectile in said case, and wherein said delaying means comprises said rear ends spaced relative to said rifling band so that the resistance thereof to the engraving action of said lands cooperates with the inertia of said projectile in delaying the displacement of said projectile from said case during the escape of the discharge gas between said thinned down portion when expanded by the discharge gas and said projectile. 